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Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

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Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#141

Post by Scaevolus »

Obi_Juan_Kenobi wrote: post #130
cletus wrote: post #118

So a lot is known at this point: 1. The A320neo caught Boeing completely off-guard; 2. The threat of the likes of American Airlines (already a mixed Airbus/Boeing customer and the largest airline in the world) placing a large A320neo order for regional aircraft operations scared the bejesus out of Boeing management; 3. For airlines like Southwest that are pure 737, the prospect of adding a plane that didn't share a c…

> These engines moving made the plane more vulnerable to a stall situation. I don't think this is correct. A lot is being made about the engine move with regard to aerodynamic behavior, but it doesn't seem at all outside of the bounds of what is considered standard. Pilots report that a similar 'light stick feel' at high AoA is already present in aircraft like the 757. It's not that the aerodynamic change was worse o…

> MCAS was there to satisfy the type rating. MCAS is not anti-stall.

MCAS's only observable intervention is to push the nose down to prevent stall, which means it is by definition anti-stall.

Boeing says MCAS is an acronym for "Maneuvering Characteristics Augmentation System", but a better name for MCAS is "Machine Controlled Anti Stall".

https://en.wikipedia.org/wiki/Maneuvering_Characteristics_Au...

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#142

Post by basicplus2 »

manigandham wrote: post #80
djsumdog wrote: post #28

What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…

There's no fundamental design flaw, the aircraft is sound. The problem came from using software systems to artificially make the plane behave like older designs to avoid entirely new training and certifications. Even that would've been acceptable and similar systems are already in use in other planes but it was the inadequate info, redundancy, warnings and controls to disable the system that created the problem. It's…

The engines we placed in a far from ideal position because of low ground clearance making the plane not fly close to neutral that is a fundamental design flaw

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#143

Post by dmix »

cletus wrote: post #118

So a lot is known at this point: 1. The A320neo caught Boeing completely off-guard; 2. The threat of the likes of American Airlines (already a mixed Airbus/Boeing customer and the largest airline in the world) placing a large A320neo order for regional aircraft operations scared the bejesus out of Boeing management; 3. For airlines like Southwest that are pure 737, the prospect of adding a plane that didn't share a c…

How hard would it be to add two more sensors to every plane? I'd imagine insanely expensive but this is clearly the ideal solution in addition to whatever patches they can do via software and existing hardware/controls in the whole plane.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#144

Post by moioci »

joe_the_user wrote: post #64
erentz wrote: post #43

Earlier quoted context omitted.

> What is the endgame now for 737 MAX planes? The bugs will be addressed and they'll still fly. Airlines have no choice, there's a limited capacity in the world for airplane construction, several thousands of orders on the books for the 737 and 320 waiting to be filled. What can an airline do? They can cut back some orders but not all orders. > I'd honestly like to see the 737 MAX taken out of service and Boeing simp…

I'm not an engineer but what about: A) Adding two more angle-of-attack sensors so a pilot can be reasonably sure of auto-adjust will work. Retrofitting those would be expensive, of course. B) Put the two buttons back the way they were and add a "light" indicator an angle-of-attack sensor failure. C) More pilot simulator training so pilots know what to expect in the unusual situation that the system fails. I suspect t…

As long as safety is regarded as a luxury feature, these failures will continue to happen.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#145

Post by hirowan »

manigandham wrote: post #136
hirowan wrote: post #132

Earlier quoted context omitted.

I don't know which one you imagine MCAS to be but see [1]; specifically: MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as requ…

I think we're talking past each other. MCAS is stability control which a lot of planes have and is allowable to pass certifications. However MCAS also makes the MAX behave like the older design which specifically led to the gap in training and controls over the system. If they just had stability control but without the emulation of behavior then there would be new training and certification, which is something they w…

There is no other modern airliner with a software bodge for static stability. No, Airbuses are not comparable (Airbus FBW control laws are _not_ for stability control) and they are (to the best of my knowledge) positively stable throughout the flight envelope in direct law.

Emulation is incidental. Redesigning the 737 with FBW is not something that Boeing would've considered, even for a moment.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#146

Post by CydeWeys »

dmix wrote: post #143
cletus wrote: post #118

So a lot is known at this point: 1. The A320neo caught Boeing completely off-guard; 2. The threat of the likes of American Airlines (already a mixed Airbus/Boeing customer and the largest airline in the world) placing a large A320neo order for regional aircraft operations scared the bejesus out of Boeing management; 3. For airlines like Southwest that are pure 737, the prospect of adding a plane that didn't share a c…

How hard would it be to add two more sensors to every plane? I'd imagine insanely expensive but this is clearly the ideal solution in addition to whatever patches they can do via software and existing hardware/controls in the whole plane.

These planes cost nearly $100M each; how can adding another AoA sensor the size of your hand be that much in the grand scheme of things? https://i.kinja-img.com/gawker-media/image/upload/t_original...

Note that the 737 already has two such sensors, but only consults one at a time for MCAS, so there'd be a software change required in addition to adding a new sensor.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#147

Post by bumby »

rootusrootus wrote: post #45
bumby wrote: post #29

Earlier quoted context omitted.

True, but this seems to sound like, "if we just hire the right people none of these safety procedures would be necessary". If we only had ethical people we wouldn't need laws. Its more important to focus on the processes rather than the individual people, especially because even great people can have off days.

My point was that we should figure out why one aircrew worked it out, and one did not. If we want to fix the process, we have to consider the humans. I get the impression from this whole debacle that one significant contributor to the accidents was that Boeing's idea of what the procedures should be and what pilots actually do is different enough to be catastrophic. Putting everything else aside for a moment, this ha…

If you're point was to consider human factors as part of the overall process, I agree

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#148

Post by dmix »

CydeWeys wrote: post #146
dmix wrote: post #143

Earlier quoted context omitted.

How hard would it be to add two more sensors to every plane? I'd imagine insanely expensive but this is clearly the ideal solution in addition to whatever patches they can do via software and existing hardware/controls in the whole plane.

These planes cost nearly $100M each; how can adding another AoA sensor the size of your hand be that much in the grand scheme of things? https://i.kinja-img.com/gawker-media/image/upload/t_original... Note that the 737 already has two such sensors, but only consults one at a time for MCAS, so there'd be a software change required in addition to adding a new sensor.

I'd just imagine coordinating with every airport and airport mechanic team to go through this process, have some integration work with the MCAS which has to be done very carefully and thoroughly. Everything is more expensive when you have a super high level of risk management and are working with large bureaucratic organizations like airlines and the FAA.

But yes it's certainly not impossible sounding. It's like a minor recall where the planes get fixed on site.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#149

Post by erichocean »

dd36 wrote: post #6
MaxBarraclough wrote: post #4

Earlier quoted context omitted.

One of the lessons learned is that the FAA is no longer a credible institution.

Gotta love deregulation. How many institutions are left? Any? CFPB, EPA, HUD, Interior are all run by people that don’t believe in their missions. It’s all about undermining from inside. Who protects the public when private rights of collective action are forbidden by arbitration agreements and the government has been captured by private interests?

> Gotta love deregulation.

I dunno, I see it as the opposite: regulation (apparently) made it impossible to just train pilots on this one new feature, instead requiring a full recertification of both the airframe and the pilots, which is incredibly expensive and unnecessary relative to what was actually required to save lives.

So one way of looking at is is: regulation caused perverse incentives that ultimately got people killed.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#150

Post by marcosdumay »

kortilla wrote: post #138
JudgeWapner wrote: post #111

Earlier quoted context omitted.

> The engine mounting certainly does not make the plane unsafe. I don't think this is a very...'precise' statement. what is "safe" in the context of aviation? If you had no MCAS, then this plane has a very bad propensity to stall . I hope we can both agree that's an unsafe airplane. You can't just say "don't do that [pull up too much] and then you're fine". The aircraft "wants" to pitch up too high and stall, which p…

No, it did not “have a bad propensity to stall”. That’s a very imprecise statement in the first place but if you take it to mean, it would try to stall during normal flight conditions, it’s definitely false. Airbus aircraft are “safe” despite the fact that dual conflicting pilot input is averaged without stick feedback (see the Airfrance flight from Brazil). If electronics being used to fly the aircraft upsets you, y…

> That’s a very imprecise statement in the first place but if you take it to mean, it would try to stall during normal flight conditions, it’s definitely false.

The precise wording would be that it is dynamically unstable, and the ball is with Boeing now to prove it's not the case. Also after all we discovered on the last weeks, Boeing better make a good case, or they won't convince anyone.

The US aviation industry is about to change. I don't know into what, but it's not in a stable situation.

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